Coating composition comprising autoxidisable component

ABSTRACT

An aqueous solution coating composition comprising an autoxidizable polyvinyl polymer having ≧20% of fatty acid residue by weight of polymer; T g  from −60 to +15° C.; acid value of 15 to 75 mg KOH/g, M w  from 2500 to 100000 g/mol; polydispersity ≦30, said composition having ≦25% co-solvent by weight of solids, ≧30% solids by weight of composition; said composition when in the form of a coating having a telegraphing value defined as the difference in gloss at a 20° angle of between a film cast on rough PVC and a film cast on smooth PVC of 10 gloss units.

This application is a continuation of commonly owned U.S. applicationSer. No. 12/919,322, filed Dec. 15, 2010 (now abandoned), which is thenational phase application under 35 USC §371 of PCT/EP2009/053824, filedMar. 31, 2009, and claims the benefit of priority of EP 08006273.0,filed Mar. 31, 2008, the entire contents of which is hereby incorporatedby reference.

The present invention relates to certain coating compositions thatcomprise an autoxidisable component and processes for making suchcompositions. Coatings of the invention show reduced telegraphing ofsurface irregularities after the composition has been applied to asurface.

There is a general need when applying a decorative or protective coatingto a substrate to obtain a smooth surface without visibleirregularities. The degree to which an underlying surface can bevisually ascertained through a coating is often described astelegraphing (i.e. giving a clumsily obvious hint or prematureindication of something to come). It has been found that irregularitieson substrates (such as wood), which contribute to the roughness, areoften telegraphed through conventional dry coatings.

Thicker coating materials are often used to reduce telegraphing becausethey are sufficiently able to level out any unevenness in the surface.Thus the underlying surface roughness of the substrate shows through toa reduced extent into the final coating which appears visually smooth.However, thicker coatings are disadvantageous because they may need tobe applied in several layers, increasing the cost. Also slowerthrough-drying, wrinkling and sagging can occur when using thickerlayers.

Organic solvents have been used to reduce telegraphing. However with acontinuing concern about the use of organic solvents there has been along felt need for an aqueous coating composition with comparableproperties to those achievable using compositions based on organicsolvents.

A coating should also dry sufficiently quickly to avoid the adherence ofdust and to ensure that the coating quickly becomes water resistant(e.g. in case of outdoor applications), blocking resistant andtack-free.

Aqueous compositions such as water dilutable autoxidisable esters (alsoknown as water dilutable unsaturated alkyds or alkyd emulsions) havealso been used to address the issue of telegraphing. However thesesystems have many well known problems.

Water dilutable alkyds may also suffer from backbone hydrolysis. Thismay lead to changes in the performance over time which is undesirable.Traditional alkyd emulsions are discussed in “Water borne and solventbased alkyds and their end user applications” by N. Tuck, volume VI,Wiley/Sita Series In Surface Coatings technology; (ISBN 471985910)published in 2000.

Another common problem of traditional alkyd emulsions is their tendencyto produce cissing (also known as crawling) when applied as anover-coat. Cissing is when a coating refuses to form a continuous film,recedes from the surface, collects in beads and leaves the surfacepartially exposed thus reducing the appearance of the painted object.

Yet another disadvantage of traditional alkyd systems, especially thosecontaining a relatively high percentage of unsaturated fatty acidresidues, is their pronounced tendency to yellow (in light or dark) overtime.

Current coatings lack some or all of the above mentioned performancecharacteristics, so coatings which exhibit reduced telegraphing with acombination of: minimal hydrolysis of the backbone of the alkyd, lowyellowing over time and/or reduced cissing are desired.

Prior aqueous coatings have not been widely accepted in many markets asalternatives to solvent based coatings. For example solvent based alkydsare still preferred in the decorative market, where very lowtelegraphing is required as these coatings are often applied by brush.It is also desired that aqueous compositions are not milky or opaque butclear or transparent.

It is also generally known that polyester based alkyds (PE alkyds)typically have a broad molecular weight distribution and thus comprise asignificant amount of material having a low molecular weight, whichdries more slowly and therefore means the coating remains tacky for alonger period (i.e. has long tack free times). The presence of materialof lower molecular weight cannot be avoided for many reasons. Forexample both glycerol (with three fatty acids—triglycerides) andpentaerythritol (with four fatty acids) are common raw materials used toprepare PE alkyds. To address the issues raised by the presence of thelow molecular weight fraction, PE alkyds may be prepared in a highlybranched form to obtain a high molecular weight fraction that dries morequickly. However the resultant branched PE alkyds have a significantlyincreased viscosity and reduced flow (compared to less branchedequivalents) and thus must be diluted with more organic solvent beforethey can be used. This is undesirable as for example it increases theamount of volatile organic compounds (VOC) and adversely affects theflow of the composition.

It is known that autoxidisable vinyl polymers may be prepared by aradical polymerisation of vinyl monomers in the presence of a fatty acidderivative. However the resultant polymers have a broad molecular weightdistribution, and these polymers require higher amounts of solvent tomake a coating, which generally also contains high levels of freemonomer. Without wishing to be bound by theory it is believed thatunsaturated fatty acids retard radical polymerisation and graft onto thevinyl polymer resulting in more material of higher molecular weight anda broader molecular weight distribution.

WO 2002-033012 (=EP 1328594) (Avecia) discloses an aqueous coatingcomposition based on a crosslinkable water-dispersable vinyl oligomerand optionally a dispersed polymer. The oligomers described in thisapplication have a low amount of fatty acid (<40% by weight). As shownby the comparative data herein these oligomers are designed for adifferent purpose (improved open time) and produce coatings which,within a few days, lack satisfactory body (in the tests as definedherein), do not produce satisfactory tack free times and become unusableafter one day.

U.S. Pat. No. 5,089,342, EP 0370299 and EP 0316732 (all Bayer) disclosean aqueous, air drying coating composition containing a water-soluble,air-drying polyacrylate with a molecular weight of more than 1000 g/moleand 5-40 wt % of chemically incorporated fatty acids and 50-100milli-equivalents per 100 grams of solid of chemically incorporatedquaternary ammonium moieties. This reference describes systems that arecationic, teaching away from using anionic systems (e.g. see col. 1,line 53) and teaches use of styrenic monomers as part of the vinylmonomers which is not ideal as it can cause yellowing in the finalproduct.

U.S. Pat. No. 5,096,959 (Valspar) discloses water based alkyd resinsthat are modified to provided increased hydrolytic stability by reactingthem with a polybasic acid composition containing one or morecycloaliphatic polybasic acids.

WO 2007-147559 (DSM) describes air drying fatty acid functionalhyperbranched resins. The resins are water soluble, due to a relativelyhigh OH content and a low fatty acid level. This is less desirable dueto the effect it has on water resistance and rate of cure and thereforeon final properties.

We have now found ways to overcome the above mentioned disadvantages,especially when combinations of more then one of the problems need to beovercome in one coating system.

It is an object of the invention to solve some or all or the problemsidentified herein. A preferred object of the invention provides a methodof improving the appearance of coated substrates, the substratescontaining visual irregularities. In a more preferred object of theinvention the method can be used with a wide variety of coatingcompositions.

The applicant has found that certain vinyl polymers prepared by radicalpolymerisation of certain vinyl/acrylic monomers may comprisesignificantly less low molecular weight fraction (like theaforementioned triglycerides) avoiding the need to use significantamounts of high molecular weight material, for example to improvedrying. The applicant has also surprisingly found that certain vinylpolymers (with specific molecular weight, PDi and T_(g) values), thatare prepared by radical polymerisation of epoxy functional vinylmonomers with other vinyl monomers, and then reacted with certainunsaturated fatty acids may overcome some or all of the above identifiedproblems with prior art vinyl polymers.

According to the present invention there is provided an aqueous coatingcomposition that comprises an autoxidisable polymer that comprisesplurality of vinyl groups where:

-   -   I) said autoxidisable polyvinyl polymer has:        -   i) fatty acid residue in an amount greater than or equal to            20% by weight of said autoxidisable polyvinyl polymer        -   ii) a glass transition temperature (T_(g)) from −60° C. to            +20° C.;        -   iii) an acid value from 5 to 75, optionally from 15 to 75 mg            KOH/g;        -   iv) a weight average molecular weight (M_(w)) from 2500 to            100000 g/mol;    -   II) said composition has:        -   a) a co-solvent content less that 25% by weight of solids;        -   b) a solids content greater than or equal to 30% by the            total weight of said composition; and    -   III) said composition when in the form of the film has a        telegraphing value of less than 10 gloss units,        -   where the telegraphing value is the difference between an            initial smooth gloss value minus an initial rough gloss            value of the film, where        -   the initial smooth gloss value is the gloss when the film is            cast on smooth PVC (R_(z)=1 μm [±0.25 μm]);        -   the initial rough gloss value is the gloss when the film is            cast on rough PVC (R_(z)=25 microns [μm] [±5 μm]); and where        -   each film has a dry film thickness of 52 μm [±6 μm]; and        -   each initial gloss value is measured at a 20° angle, one day            (24 hours) after the film has been cast.

As used herein PVC means a polyvinylchloride substrate used as describedin the test methods herein.

Dry film thickness herein is measured after 24 hours of drying, understandard conditions. As used herein, unless the context indicatesotherwise, the term ‘standard conditions’ denotes a relative humidity of50%±5%, an air flow less than or equal to 0.1 m/s; and an ‘ambienttemperature’ which herein denotes 23° C.±2°.

The telegraphing values herein will be positive numbers. In general thegreater the reduction in telegraphing, the smaller will be thetelegraphing value.

The term “comprising” as used herein means that the list thatimmediately follows is non exhaustive and may or may not include anyother additional suitable items, for example one or more furtherfeature(s), component(s), ingredient(s) and/or substituent(s) asappropriate. “Substantially comprising” as used herein means a componentor list of component(s) is present in a given material in an amountgreater than or equal to about 90%, preferably ≧95%, more preferably≧98% by weight of the total amount of the given material. The term“consisting of” as used herein mean that the list that follows isexhaustive and does not include additional items.

For all upper and lower boundaries of any parameters given herein, theboundary value is included in each range for each parameter. Allcombinations of minimum and maximum values of the parameters describedherein may be used to define the parameter ranges for variousembodiments and preferences of the invention.

It will be understood that the total sum of any quantities expressedherein as percentages cannot (allowing for rounding errors) exceed 100%.For example the sum of all components of which the composition of theinvention (or part(s) thereof) comprises may, when expressed as a weight(or other) percentage of the composition (or the same part(s) thereof),total 100% allowing for rounding errors. However where a list ofcomponents is non-exhaustive the sum of the percentage for each of suchcomponents may be less than 100% to allow a certain percentage foradditional amount(s) of any additional component(s) that may not beexplicitly described herein.

As used herein the terms oligomer and polymer both refer tomacromolecules which comprises a plurality of units derived, actually orconceptually, from molecules of lower molecular mass. These terms mayalso be used adjectivally to describe a part or the whole of amacromolecule. Often the term oligomer may be used more specifically torefer to macromolecules of intermediate relative molecular mass, wherethe oligomer properties vary significantly with the removal of one or afew units. Polymer may be used both generally to refer to anymacromolecule and also more specifically to refer to macromolecules ofhigh relative molecular mass where usually addition or removal of one ora few units has a negligible effect on the molecular properties(although this may not be always be the case for example where polymershave certain properties that are critically dependent on fine details ofthe molecular structure). It will be understood that the molecular massboundary between an oligomer and a polymer (in its specific rather thangeneral meaning) may vary according to the specific macromolecule and/orapplications of interest and so they may be significant overlap wherethe same macromolecules may be considered both a oligomer and a polymer.Therefore, unless the context herein clearly indicates otherwise, theterms oligomer and polymer are used herein interchangeably.

Preferably the coating compositions of the invention are non-adhesivecompositions. As used herein the term ‘non-adhesive composition’ denotesany composition that does not remain substantially tacky after dryingunder standard conditions for a length of time which would becommercially acceptable. Preferred non-adhesive compositions are thosewhich have a tack-free time of less than 16 hours, more preferably <10hours, most preferably <6 hours. Tack free time may conveniently bemeasured as described herein.

Compositions of the invention may be aqueous solutions or emulsionswhere the continuous phase is aqueous, although aqueous solutions arepreferred.

Preferred compositions of the invention produce coatings that have atelegraphing value (as defined herein) of less than 7 gloss units, morepreferably less than 4.5 gloss units.

Preferably the initial rough gloss should not deteriorate significantlyover time. This can be measured as a ‘gloss decay’ defined as theinitial rough gloss minus a rough gloss measured at a later specifiedtime. For example “gloss decay (‘n’ days)” is calculated as the initialrough gloss (measured 1 day after film formation) minus the rough glossmeasured ‘n’ days after film formation (i.e. in this case n isalways >1). Preferably the gloss decay is measured 4 days, morepreferably 7 days and most preferably 14 days after film formation.Preferred values of gloss decay (for example after each of the periodsgiven above) are less than 10 gloss units, more preferably less than 7gloss units, most preferably less than 5 gloss units.

Without wishing to be bound by any theory it is believed that the vinylpolymers of the invention have a comb like structure allowing excellentcontrol of molecular weight distribution to give a relatively narrowdistribution resulting in good flow, reduced telegraphing and fastdrying. Conventional vinyl polymers are typically highly branched andused under conditions which are close to those which cause the polymerto gel. In contrast the vinyl polymers of the invention arehydrolytically stable as their backbone is more resistant to hydrolysis.These properties are especially important for decorative paints whichmay stay on the shelf for a long time.

Polymers of the invention have a narrow molecular weight distribution(which may be measured as a polydispersity, PDi) and a relatively lowweight average molecular weight (Mw) and therefore an improved Mw/PDibalance. As these polymers have less material of low molecular weight,they produce coating compositions that dry fast, for example have shortdust and/or tack free times. Compositions of the invention have otheradvantages. They may be prepared with lower viscosities due to thereduced amount of high molecular weight material and for example insolvent borne systems, less solvent is needed to achieve a certainviscosity and in aqueous systems lower viscosity can reducetelegraphing. Alternatively compositions with a similar solvent contentto the prior art can be produced with a higher overall molecular weight.Compositions of the invention can also be prepared with a high solidscontent.

Preferably the autoxidisable polyvinyl polymer will crosslink at ambienttemperature. Crosslinking by autoxidation means the crosslinking resultsfrom an oxidation occurring in the presence of air, usually involving afree radical mechanism and is preferably metal-catalysed resulting incovalent bonds. Suitable autoxidation is provided by for example fattyacid residues comprising unsaturated bonds, allyl functional residuesand/or β(beta)-keto ester groups preferably by fatty acid residuescomprising unsaturated bonds.

As used herein ‘fatty acid residue’ (or FA residue), means fatty acids,simple derivatives thereof (such as esters (e.g. C₁₋₄alkyl esters),salts, soaps, oils, fats and/or waxes) and mixtures thereof. As usedherein ‘fatty acid’ means any predominately unbranched, non-cyclic(preferably substantially linear) aliphatic carboxylic acid thatsubstantially comprises, preferably consists of an aliphatic hydrocarbonchain and at least one carboxy group, preferably a single terminalcarboxyl group (i.e. located at the end of the chain). Fatty acids maycomprise a limited number of other substituents such as hydroxyl and maybe saturated, mono-unsaturated or poly-unsaturated.

The fatty acid residue may be obtained from one or more natural and/orartificial source. Natural sources include animal sources and/or plantsources. Animal sources may comprise animal fat, butter fat, fish oil,lard, liver fats, sperm whale oil and/or tallow oil and waxes. Examplesof waxes are beeswax, candelia and/or montan. Plant sources may comprisewaxes and/or oils such as vegetable oils and/or non-vegetable oils.Examples of plant oils are: bitter gourd, borage, calendula, canola,castor, china wood, coconut, conifer seed, corn, cottonseed, dehydratedcastor, flaxseed, grape seed, Jacaranda mimosifolia seed, linseed,olive, palm, palm kernel, peanut, pomegranate seed, rapeseed, safflower,snake gourd, soya(bean), sunflower, tung, and/or wheat germ. Artificialsources include synthetic waxes (such as micro crystalline and/orparaffin wax), distilling tall oil (a by-product of processing pinewood) and/or synthesis (for example by chemical and/or biochemicalmethods). Fatty acid residues having conjugated double bonds may beobtained by catalytic isomerisation of natural fatty acids and/ordehydrated castor oil. Conjugated oils are preferably obtained bydehydration of castor oil. Fatty acid residues may be obtained and/orobtainable from a plurality of the above sources and/or other sourcesnot listed herein.

Preferred fatty acid residues may comprise fatty acid(s) having from 4to 36, more preferably from 8 to 26, most preferably from 10 to 24,especially 12 to 22 carbon atoms. Generally fatty acids obtained fromnatural sources have an even number of carbon atoms due to their methodof biosynthesis, however fatty acids with an odd number of carbon atomsmay also be useful in the present invention. Fatty acid residues maycomprise fatty acids with one or more carboxylic acid groups, forexample dimer or trimer fatty acids. However preferred fatty acids aremono functional, more preferably C₁₀₋₂₄mono functional carboxylic acids,most preferably C₁₂₋₂₂linear mono functional terminal carboxy acids.

As long as oxidative drying of the polymer is not impaired the fattyacid residue may comprise one or more saturated fatty acids and/or oils,however at least some unsaturated fatty acid(s) is needed forauto-oxidation to occur. In general the more unsaturation present themore rapid the autoxidiative drying.

An iodine number may be used to indicate the amount of unsaturationcontained in fatty acids where a higher the iodine number indicates moreunsaturated double bonds are present. Preferably the fatty acid residueused herein has an average iodine value greater than or equal to 50,more preferably ≧80 and most preferably ≧100 g I₂/100 g fatty acid.Preferably the fatty acid residue used herein has an average iodinevalue less than or equal to 200, more preferably ≦180 and mostpreferably ≦150 g I₂/100 g fatty acid. The iodine value may be measuredconventionally or preferably as described in the test methods herein.

For the purpose of determining the amount of fatty acid residue used toobtain the polyvinyl polymer of the invention, it is convenient tocalculate the weight of the fatty acid reactant by including thecarbonyl group, but excluding the hydroxyl group of the terminal acidgroup of the fatty acid molecule.

Preferably the minimum amount of fatty acid residues in theautoxidisable vinyl polymer is greater than or equal to 28%, morepreferably ≧38% and most preferably ≧43% by weight of the polymer.

Preferably the maximum amount of fatty acid residue in the autoxidisablevinyl polymer is less than or equal to 70%, more preferably ≦65% andmost preferably ≦55% by weight of the polymer.

Preferably the fatty acid residue comprises C₁₀₋₃₀ fatty acids, morepreferably C₁₆₋₂₀ fatty acids, in an amount greater than or equal to 80%by weight of the fatty acid residue. More preferably the fatty acidresidue substantially comprises, most preferably consists of C₁₀₋₃₀fatty acids, especially C₁₆₋₂₀ fatty acids.

If the fatty acid residue comprises saturated fatty acids they may bepresent in an amount less than or equal to 40%, more preferably ≦20% andmost preferably from 3% to 18% by weight of the fatty acid residue.

Preferred polyvinyl polymers are those in which the autoxidisable groupsare mainly derived from fatty acid residue. More preferably the fattyacid residue mainly comprises, most preferably substantially comprisesunsaturated fatty acids. Useful unsaturated fatty acids have two or moredouble bonds, more usefully are conjugated fatty acids.

An embodiment of the invention provides polyvinyl polymers withautoxidisable groups mainly derived from unsaturated fatty acids havingtwo or more double bonds, preferably conjugated fatty acids. Morepreferably at least 40%, most preferably at least 60% by weight of thetotal amount of unsaturated fatty acids are those fatty acids thatcontain at least two unsaturated groups.

The autoxidisable polyvinyl polymer may be obtained from a mixture ofconjugated and non-conjugated unsaturated fatty acids. Preferably theautoxidisable polymer is obtained and/or obtainable from a mixture ofunsaturated fatty acids that comprises 20% to 70% of conjugated and 80%to 30% of non-conjugated fatty acids by weight of the total amount ofunsaturated fatty acids.

A known problem with many autoxidisable coating compositions is that theresultant coatings have a tendency to yellow, in particular where theautoxidisable groups are derived from polyunsaturated fatty acids (e.g.those described herein). This may be unacceptable depending on thedesired color of the resultant coating.

Therefore in another embodiment of the invention to reduce yellowing,preferred autoxidisable vinyl oligomers are those where the unsaturatedfatty residue comprises low amounts of highly polyunsaturated fattyacids. For example vinyl polymers that are more resistant to yellowingmay be obtained and/or obtainable from fatty acid residues that compriseby weight of total fatty acid no more than 10%, more preferably <7%,most preferably <4% and especially <2% of fatty acids with three or moredouble bonds. Examples of fatty acids that include three or more doublebonds are given herein.

Preferred compositions of the invention have an initial yellowness valueof less than or equal to 10, more preferably ≦7 and most preferably ≦4,when measured using the test method described herein. Preferredcompositions show only a small increase in yellowness (Δb value) afterbeing held in darkness for 3 weeks at 52° C., more preferably Δb is lessthan or equal to 10, still more preferably is ≦7, most preferably ≦5 andespecially ≦3.

In yet another embodiment of the invention (e.g. where yellowing is nota concern) preferred autoxidisable vinyl oligomers are those where theunsaturated fatty residue comprises higher amounts of highlypolyunsaturated fatty acids (such as fatty acids with three or moredouble bonds) as this can improve the speed of autoxidative drying.

Preferably the unsaturated fatty acid is covalently bound to the vinyloligomer in a one step process, either though the use of a fatty acidfunctional vinyl monomer or through a reaction of the fatty acid withthe vinyl oligomer.

It is preferred that glycidyl esters of unsaturated fatty acids are notused in the preparation of the autoxidisable vinyl oligomer as thesynthesis of these glycidyl esters requires toxic raw materials likeepichlorohydrine which will also give chlorine containing waste materialwhich is undesirable. A glycidyl ester of an unsaturated fatty acid isan epoxy functional fatty acid material (usually with a number averagemolecular weight (M_(n)) below 400) where the acid group has beenreacted to obtain a glycidyl end group.

Optionally the fatty acid residue may also comprise one or more alkynylgroup(s) and/or one or more (non carboxy) hydroxyl group(s).

Non limiting examples of some common fatty acids that may be used in thepresent invention are listed below as their systematic (IUPAC) nameswith their trivial name(s) in square parentheses where known. It will beappreciated that in practice most fatty acid residues (especially thoseobtained from natural sources) will comprise a mixture of many of theseacids as well as other acids not specifically listed herein.

Saturated fatty acids may be selected from:

butanoic [butyric] acid (C₄H₈O₂), pentanoic [valeric] acid (C₅H₁₀O₂),hexanoic [caproic] acid (C₆H₁₂O₂), heptanoic [enanthic] acid (C₇H₁₄O₂),octanoic [caprylic] acid (C₈H₁₆O₂), nonanoic [pelargonic] acid(C₉H₁₈O₂), decanoic [capric] acid (C₁₀H₂₀O₂), dodecanoic [lauric] acid(C₁₂H₂₄O₂), tetradecanoic [myristic] acid (C₁₄H₂₈O₂), hexadecanoic[palmitic] acid (C₁₆H₃₂O₂), heptadecanoic [margaric also daturic] acid(C₁₇H₃₄O₂), octadecanoic [stearic] acid (C₁₈H₃₆O₂), eicosanoic[arachidic] acid (C₂₀H₄₀O₂), docosanoic [behenic] acid (C₂₂H₄₄O₂),tetracosanoic [lignoceric] acid (C₂₄H₄₈O₂), hexacosanoic [cerotic] acid(C₂₆H₅₂O₂), heptacosanoic [carboceric] acid (C₂₇H₅₄O₂), octacosanoic[montanic] acid (C₂₈H₅₆O₂), triacontanoic [melissic] acid (C₃₀H₆₀O₂),dotriacontanoic [lacceroic] acid (C₃₂H₆₄O₂), tritriacontanoic[ceromelissic also psyllic] acid (C₃₃H₆₆O₂), tetratriacontanoic [geddic]acid (C₃₄H₆₈O₂) and/or pentatriacontanoic [ceroplastic] acid (C₃₄H₇₀O₂).

Mono-unsaturated fatty acids may be selected from:

(Z)-decan-4-enoic [obtusilic] acid (C₁₀H₁₈O₂), (Z)-decan-9-enoic[caproleic] acid (C₁₀H₁₈O₂), (Z)-undecan-10-enoic [undecylenic also10-hendecenoic] acid (C₁₁H₂₀O₂), (Z)-dodan-4-ecenoic [linderic] acid(C₁₂H₂₂O₂), (Z)-dodecan-5-enoic (lauroleic) acid (C₁₂H₃₀O₂),(Z)-tetradecan-4-enoic [tsuzuic] acid (C₁₄H₂₆O₂), (Z)-tetradecan-5-enoic[physeteric] acid (C₁₄H₂₆O₂), (Z)-tetradecan-9-enoic [myristoleic] acid(C₁₄H₂₆O₂), (Z)-hexadan-6-enoic [sapienic] acid (C₁₆H₃₀O₂),(Z)-hexadan-9-enoic [palmitoleic] acid (C₁₆H₃₀O₂), (Z)-octadecan-6-enoic[petroselinic] acid (C₁₈H₃₄O₂), (E)-octadecan-9-enoic [elaidic] acid(C₁₈H₃₈O₂), (Z)-octadecan-9-enoic [oleic] acid (C₁₈H₃₄O₂),(Z)-octadecan-11-enoic [vaccenic also asclepic] acid (C₁₈H₃₄O₂),(Z)-eicosan-9-enoic [gadoleic] acid (C₂₀H₃₈O₂), (Z)-eicosan-11-enoic[gondoic] acid (C₂₀H₃₈O₂), (Z)-docosan-11-enoic [cetoleic] acid(C₂₂H₄₂O₂), (Z)-docosan-13-enoic [erucic] acid (C₂₂H₄₂O₂) and/or(Z)-tetracosan-15-enoic [nervonic] acid (C₂₄H₄₆O₂).

Di-unsaturated fatty acids may be selected from:

(5Z,9Z)-hexadeca-5,9-dienoic acid (C₁₆H₂₈O₂),(5Z,9Z)-octadeca-5,9-dienoic [taxoleic] acid (C₁₈H₃₂O₂),(9Z,12Z)-octadeca-9,12-dienoic [linoleic] acid (C₁₈H₃₂O₂),(9Z,15Z)-octadeca-9,15-dienoic acid (C₁₈H₃₂O₂) and/or(7Z,11Z)-eicosa-7,11-dienoic [dihomotaxoleic] acid (C₂₀H₃₆O₂).

Tri-unsaturated fatty acids may be selected from:

(5Z,9Z,12Z)-heptadeca-5,9,12-trienoic acid (C₁₇H₂₈O₂),(3Z,9Z,12Z)-octadeca-3,9,12-trienoic acid (C₁₈H₃₀O₂),(5Z,9Z,12Z)-octadeca-5,9,12-trienoic [pinolenic] acid (C₁₈H₃₀O₂),(6Z,9Z,12Z)-octadeca-6,9,12-trienoic acid [γ(gamma)-linolenic acid alsoGLA] (C₁₈H₃₀O₂), (8E,10E,12Z)-octadeca-8,10,12-trienoic [calendic] acid(C₁₈H₃₀O₂), (8Z,10E,12Z)-octadeca-8,10,12-trienoic [jacaric] acid(C₁₈H₃₀O₂), (9E,11E,13E)-octadeca-9,11,13-trienoic [β(beta)-eleostearicalso β-oleostearic] acid (C₁₈H₃₀O₂),(9E,11E,13Z)-octadeca-9,11,13-trienoic [catalpic] acid (C₁₈H₃₀O₂),(9Z,11E,13E)-octadeca-9,11,13-trienoic [α(alpha)-eleostearic alsoα-oleostearic] acid (C₁₈H₃₀O₂) (where α-eleostearic acid comprises >65%of the fatty acids of tung oil), (9Z,11E,13Z)-octadeca-9,11,13-trienoic[punicic also trichosanic] acid (C₁₈H₃₀O₂),(9Z,11E,15Z)-octadeca-9,11,13-trienoic [rumelenic] acid (C₁₈H₃₀O₂),(9Z,13E,15Z)-octadeca-9,13,13-trienoic acid (C₁₈H₃₀O₂),(9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid [α(alpha)-linolenic acidalso ALA] (C₁₈H₃₀O₂), (5Z,8Z,11Z)-eicosa-5,8,11-trienoic[dihomo-γ(gamma)-linolenic] acid (C₂₀H₃₄O₂),(5Z,11Z,14Z)-eicosa-8,11,14-trienoic [sciadonic] acid (C₂₀H₃₄O₂) and/or(8Z,11Z,14Z)-eicosa-8,11,14-trienoic [Mead] acid (C₂₀H₃₄O₂).

Tetra-unsaturated fatty acids may be selected from:

(6Z,8Z,10Z,12Z)-hexadeca-6,8,10,15-tetraenoic acid (C₁₆H₂₄O₂),(6Z,8Z,10Z,12Z)-octadeca-6,8,10,12-tetraenoic acid (C₁₈H₂₈O₂),(6Z,9Z,12Z,15Z)-octadeca-6,9,12,15-tetraenoic [stearidonic] acid(C₁₈H₂₈O₂), (9Z,11E,13E,15Z)-octadeca-9,11,13,15-tetraenoic[α(alpha)-parinaric] acid (C₁₈H₂₈O₂),(9Z,11Z,13Z,15Z)-octadeca-9,11,13,15-tetraenoic [β(beta)-parinaric] acid(C₁₈H₂₈O₂), (5Z,8Z,11Z,14Z)-eicosa-5,8,11,14-tetraenoic acid[arachidonic acid also AA] (C₂₀H₃₂O₂),(6Z,8Z,10Z,12Z)-eicosa-6,8,10,12-tetraenoic acid (C₂₀H₃₂O₂),(8Z,11Z,14Z,11Z)-eicosa-8,11,14,17-tetraenoic acid (C₂₀H₃₂O₂),(6Z,8Z,10Z,12Z)-docosa-6,8,10,12-tetraenoic acid (C₂₂H₃₆O₂) and/or(7Z,10Z,13Z,16Z)-docosa-7,10,13,16-tetraenoic acid (C₂₂H₃₆O₂).

Penta-unsaturated fatty acids may be selected from:

(x,6Z,8Z,10Z,12Z)-hexadeca-x,6,8,10,12-pentaenoic acid(s) (C₁₆H₂₂O₂)where x denotes a fifth double bond optionally in a position which doesnot conjugate with the other four conjugated ethylenic double bonds,(x′,6Z,8Z,10Z,12Z)-eicosa-x′,6,8,10,12-pentaenoic acid(s) (C₂₀H₃₀O₂)where x′ denotes a fifth double bond optionally in a position which doesnot conjugate with the other four ethylenic double bonds,(5E,7E,9E,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid (C₂₀H₃₀O₂),(5Z,7E,9E,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid (C₂₀H₃₀O₂),(5Z,8Z,11Z,14Z,17Z)-eicosa-5,8,11,14,17-pentaenoic acid [EPA](C₂₀H₃₀O₂), (7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoic[clupanodonic] acid (C₂₂H₃₄O₂),(4Z,7Z,10Z,13Z,16Z)-docosa-4,7,10,13,16-pentaenoic [osbond] acid(C₂₂H₃₄O₂) and/or (7Z,10Z,13Z,16Z,19Z)-docosa-7,10,13,16,19-pentaenoicacid [DPA] (C₂₂H₃₄O₂).

Hexa-unsaturated fatty acids may be selected from:

(x″,y″,6Z,8Z,10Z,12Z)-eicosa-x″,y″,6,8,10,12-hexaenoic acid(s)(C₂₀H₂₈O₂) where x″ and y″ denote fifth and sixth double bondsoptionally in positions which do not conjugate with the other fourconjugated ethylenic double bonds,(4Z,7Z,10Z,13Z,16Z,19Z)-docosa-4,7,10,13,16,19-hexaenoic acid [DHA](C₂₂H₃₂O₂) and/or(6Z,9Z,12Z,15Z,18Z,21Z)-tetracosa-6,9,12,15,18,21-hexaenoic [nisinic]acid (C₂₄H₃₆O₂).

Hepta-unsaturated fatty acids may be selected from:

(w″′,x′″,y′″,6Z,8Z,10Z,12Z)-eicosa-w′″,x″′,y′″,6,8,10,12-heptaenoicacid(s) (C₂₂H₃₀O₂) where w″′, x′″ and y′″ denote fifth, sixth and sevendouble bonds optionally in positions which do not conjugate with theother four conjugated ethylenic double bonds, and/or(4Z,7Z,9Z,11Z,13Z,16Z,19Z)-docosa-4,7,9,11,13,16,19-heptaenoic[stellaheptaenoic] acid (C₂₂H₃₀O₂).

Alkynyl-functional fatty acids may be selected from:

(9Z)-octadeca-9-en-12-ynoic [crepenynic] acid (C₁₈H₃₀O₂).

Hydroxy-functional fatty acids may be selected from:

12-hydroxy-(9Z)-octadeca-9-enoic [ricinoleic] acid (C₁₈H₃₄O₃).

Optionally autoxidation is used in combination with other crosslinkingmechanisms as are known in the art. In an embodiment, metal ioncrosslinking may be used in combination with the autoxidation mechanism,e.g. by use of coordinative driers as is well known by those skilled inthe art. Other crosslinking mechanisms known in the art that may also beused in combination with autoxidation include the reaction ofalkoxysilane functional groups, Schiff base crosslinking, epoxy groupsreacting with amino, carboxylic acid or mercapto groups, the reaction ofamine or mercapto groups with ethylenically unsaturated groups such asfumarate and acryloyl groups, the reaction of masked epoxy groups withamino or mercapto groups, the reaction of isothiocyanates with amines,alcohols or hydrazines, the reaction of amines (for example ethylenediamine or multifunctional amine terminated polyalkylene oxides) withβ-diketo (for example acetoacetoxy or acetoamide) groups to formenamines.

The autoxidisable vinyl polymer may contain bound hydrophilicwater-dispersing groups. Suitable hydrophilic groups are well known inthe art, and can be ionic water-dispersing groups or non-ionicwater-dispersing groups. Preferred non-ionic water-dispersing groups arepolyalkylene oxide groups, more preferably polyethylene oxide groups. Asmall segment of the polyethylene oxide group can be replaced by apropylene oxide segment and/or butylene oxide segment, however thepolyethylene oxide group should still contain ethylene oxide (EO) as amajor component. When the water-dispersible group is polyethylene oxide,the preferred EO chain length is ≧4, more preferably ≧8 and mostpreferably ≧15 EO units. Preferably if the autoxidisable vinyl polymercontains polyalkylene oxide groups, the vinyl polymer has a polyalkyleneoxide (optionally EO) content which is at least ≧0%, more preferably≧2%, most preferably ≧3.5% and especially ≧5% and/or is no more than≦50%, more preferably ≦30%, most preferably ≦15% and especially ≦9% byweight of the autoxidisable vinyl polymer. Preferably the polyalkyleneoxide (optionally EO) group has a M_(w) from 175 to 5000 g/mol, morepreferably from 350 to 2200 g/mol, most preferably from 660 to 2200g/mol.

Preferred ionic water-dispersing groups are anionic water-dispersinggroups, especially carboxylic, phosphate, phosphonate and/or sulphonicacid groups. Most preferred are carboxylic, phosphate and/or phosphonategroups. The anionic water-dispersing groups are preferably fully orpartially in the form of a salt. Conversion to the salt form isoptionally effected by neutralisation of the autoxidisable polymer witha base, preferably during the preparation of the autoxidisable polymerand/or during the preparation of the composition of the presentinvention. The anionic dispersing groups may in some cases be providedby the use of a monomer having an already neutralised acid group in theautoxidisable polymer synthesis so that subsequent neutralisation isunnecessary. If anionic water-dispersing groups are used in combinationwith a non-ionic water-dispersing group, neutralisation may not berequired.

If the anionic water-dispersing groups are neutralised, the base used toneutralise the groups is preferably, an amine or an inorganic base.Suitable amines include tertiary amines, for example triethyl amine orN,N-dimethylethanolamine. Suitable inorganic bases include alkalihydroxides and carbonates, for example lithium hydroxide, sodiumhydroxide, or potassium hydroxide. Generally a base is used which givesthe required counter ion desired for the composition. For example,preferred counter ions include tertiary amines or Li⁺, Na⁺, K⁺, NH₄ ⁺and substituted ammonium salts (for example a quaternary ammoniumhydroxide ⁺N(CH₃)₄OH⁻).

Cationic water dispersible groups can also be used, but are lesspreferred. Examples include pyridine groups, imidazole groups and orquaternary ammonium groups which may be neutralised or permanentlyionised. Due to the influence that neutralisation agents have onyellowing, tertiary amines and/or LiOH, NaOH and KOH are especiallypreferred.

The autoxidisable polyvinyl polymer preferably has an acid value (AV,also referred to as an acid number [AN]) greater than or equal to 20,more preferably ≧25 mg KOH/g. The autoxidisable polymer preferably hasan acid value of less than or equal to 65, more preferably ≦60 mg KOH/g.

The autoxidisable polyvinyl polymer, if carboxylic acid functional,preferably conforms to the following relationship (where ND denotes thedegree to which the acid groups of the polymer are neutralised):

ND×AV>22, more preferably >27 and most preferably >33 mg KOH/g.

ND×AV≦65, more preferably ≦60 and most preferably <45 mg KOH/g.

ND is a dimensionless fraction from 0 to 1 that indicates of the amountof neutralizing agent present in the polymer. For example if 80% of theacid groups on the polymer are neutralised, then the ND value is 0.8. AVis reported in units of mg KOH/g so the product ND×AV has units of mgKOH/g.

The autoxidisable polyvinyl polymer preferably has an hydroxyl number of≦60 mg KOH/g, more preferably ≦40 mg KOH/g, more preferably ≦25 mgKOH/g.

Preferably the aqueous coating composition has a pH>5.1, morepreferably >6.5. Preferably the composition has a pH<9.2, morepreferably <8.4 and especially <7.6.

The aqueous coating composition preferably comprises ≧30%, morepreferably ≧35% and especially ≧40% by weight of the autoxidisablepolymer of the invention. The aqueous coating composition preferablycomprises ≦60%, more preferably ≦55%, and most preferably ≦50% by weightof the autoxidisable polymer of the invention.

The drying process of the aqueous coating composition can be dividedinto stages for example the period of time necessary to achievedust-free, tack-free coatings using the tests described herein.

Preferably the dust free time is ≦4 hours, more preferably ≦2 hours andmost preferably ≦50 minutes.

Preferably the tack-free time is ≦16 hours, more preferably ≦8 hours andmost preferably ≦5 hours.

Preferably the weight average (M_(w)) of the autoxidisable vinyl polymeris at least ≧3500, more preferably ≧5000, most preferably ≧7000, and/oris no more than ≦40000 more preferably ≦25000, most preferably ≦15000g/mol. M_(w) is measured by GPC using polystyrene standards as describedherein.

Preferably the significant part of any crosslinking reaction takes placeonly after the aqueous coating composition has been applied to asubstrate. This avoids any excessive increase in molecular weight in theearly stages of drying (and a consequent viscosity increase in thecoating).

The molecular weight distribution (MWD) of the polyvinyl polymer has aninfluence on the viscosity of the composition and hence an influence onthe telegraphing. MWD is conventionally described by a polydispersityindex (PDi) defined as the weight average molecular weight (M_(w))divided by the number average molecular weight (M_(n)) and isdimensionless. It has been found that a lower PDi often results in lowerviscosity for a crosslinkable autoxidisable polymer of given M_(w)Preferably the autoxidisable vinyl polymer has a PDi which is no morethan ≦20, more preferably ≦16 and more preferably ≦12 and/or is at least≧2.5.

Preferably the weight average particle size of the autoxidisable vinylpolymer dispersed in an aqueous coating composition is no more than ≦120nm, more preferably ≦90 nm, most preferably ≦50 nm. Preferably at least80% of the particles have a weight average particle size ≦120 nm, morepreferably ≦80 nm, most preferably ≦50 nm.

Weight average particle size can be measured by any suitable method suchas that described in the test methods herein.

The glass transition temperature (T_(g)) (as measured by DSC of a solidmaterial) of the autoxidisable vinyl oligomer may vary within a widerange and preferably is at least ≧−60° C., more preferably ≧−50° C.,still more preferably ≧−40° C. most preferably ≧−35° C. and especially≧−30° C. and/or preferably is no more than ≦+15° C., more preferably≦+10° C., most preferably ≦+5° C. and especially ≦0° C. Conveniently theT_(g) of the autoxidisable polyvinyl polymer is −1° C.

If the T_(g) can not be measured by DSC because the first derivative ofthe DSC curve does not show any identifiable maximum, an alternativemethod for determining the T_(g) is by calculating the T_(g) using thefollowing equation that relates viscosity of the pure vinyl oligomer toits T_(g) (which is derived from the Williams-Landau-Ferry [WLF]equation):Ln(η)=27.6−[40.2×(T−T _(g))]/[51.6+(T−T _(g))]where:

-   -   Ln(η)=Natural logarithm of the viscosity of the pure oligomer        expressed in Pa·s (measured at ambient temperature using a shear        rate from 0.005 and 1 s⁻¹)    -   T=23° C.±1° C. (i.e. ambient temperature is used to measure the        viscosity of the pure oligomer) and    -   T_(g)=glass temperature expressed in ° C.

Functional groups (such as fatty acid residue or water-dispersinggroups) may be introduced into the autoxidisable polyvinyl polymer usingtwo general methods: i) by using monomers carrying the functional groupin the polymerisation process to form autoxidisable polyvinyl polymercarrying the functional group; or ii) using monomers bearing selectedreactive groups where monomer is subsequently reacted with a compoundcarrying the functional group and also a reactive group of the typewhich will react with the selected reactive groups on the monomer toprovide attachment of the functional group to the autoxidisablepolyvinyl polymer via covalent bonding.

The polyvinyl autoxidisable polymer, may be prepared from free radicallypolymerisable olefinically unsaturated monomer(s), and can containpolymerised units of a wide range of such monomers, especially thosecommonly used to make binders for the coatings industry. By a vinylpolymer herein is meant a homo- or co-polymer derived from additionpolymerisation, using a free radical initiated process which may becarried out in an aqueous or non-aqueous medium, of one or moreolefinically unsaturated monomers. Therefore by a vinyl monomer is meantan olefinically unsaturated monomer.

Examples of vinyl monomers which may be used to form a vinyl polymerinclude but are not limited to 1,3-butadiene, isoprene, styrene,α-methyl styrene, divinyl benzene, acrylonitrile, methacrylonitrile,vinyl halides such as vinyl chloride, vinylidene halides such asvinylidene chloride, vinyl ethers, vinyl esters such as vinyl acetate,vinyl propionate, vinyl laurate, and vinyl esters of versatic acid suchas VeoVa 9 and VeoVa 10 (VeoVa is a trademark of Shell), heterocyclicvinyl compounds, alkyl esters of mono-olefinically unsaturateddicarboxylic acids (such as di-n-butyl maleate and di-n-butyl fumarate)and, in particular, esters of acrylic acid and methacrylic acid ofFormula 1CH₂═CR¹—COOR¹  Formula 1where R¹ is H or methyl and R² is optionally substituted C₁₋₂₀ alkyl(preferably C₁₋₈alkyl) or optionally substituted C₃₋₂₀ cycloalkyl(preferably C₃₋₈ cycloalkyl), examples of which are methyl acrylate,methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butylacrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexylmethacrylate, isopropyl acrylate, isopropyl methacrylate, n-propylacrylate, n-propyl methacrylate, and hydroxyalkyl (meth)acrylates suchas hydroxyethyl acrylate, hydroxyethyl methacrylate, 2-hydroxypropylmethacrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate,4-hydroxybutyl methacrylate and their modified analogues like Tone M-100(Tone is a trademark of Union Carbide Corporation).

Ethylenically unsaturated monocarboxylic, sulphonic and/or dicarboxylicacids, such as acrylic acid, methacrylic acid, β-carboxy ethyl acrylate,fumaric acid and/or itaconic acid may be used. Ethylenically unsaturatedmonomers such as (meth)acrylamide and/or methoxypolyethyleneoxide(meth)acrylate may also be used.

The vinyl monomer may optionally contain functional groups to contributeto the crosslinking of the vinyl polymer(s) in the coating. Examples ofsuch groups include maleic, epoxy, fumaric, acetoacetoxy, β-diketone,unsaturated fatty acid, acryloyl, methacrylol, styrenic, (meth)allylgroups, mercapto groups, keto or aldehyde groups (such asmethylvinylketone [MEK], diacetoneacrylamide and (meth)acrolein).

Preferred vinyl polymers have a backbone made from a monomer systemcomprising at least 40% of one or more monomers of Formula I by weightof the polymer. Such a preferred backbone for the vinyl polymer isdefined herein as an (meth)acrylic polymer. A particularly preferredautoxidisable vinyl polymer is an autoxidisable acrylic polymer (i.e.based predominantly on at least one ester of acrylic and/or methacrylicacid). More preferably, the monomer system for the vinyl backbonecomprises at least 50%, most preferably at least 60% of such monomers byweight of polymer. The other monomer(s) in such acrylic autoxidisablevinyl polymers (where used) may include one or more of the other vinylmonomers mentioned above, and/or may include monomer(s) different tosuch other monomers.

Particularly preferred monomers include butyl acrylate (all isomers),butyl methacrylate (all isomers), methyl methacrylate, ethyl hexylmethacrylate, esters of (meth)acrylic acid, acrylonitrile, vinyl acetateand styrene. Alternatively vinyl functional monomers with anautoxidisable moiety can be used, such as the reaction product of GMAand fatty acid and/or that monomer available commercially from ServoCondea under the trade name SerAD FX521.

In a preferred embodiment a polyvinyl polymer is prepared, which issubsequently reacted to obtain an autoxidisable polymer of theinvention.

Monomers “G” which are useful for grafting the fatty acid onto the vinylpolymer to give fatty acid residues includehydroxylalkyl(meth)acrylates, such as hydroxyethyl(meth)acrylate,hydroxypropyl(meth)acrylate and ToneM-100 and preferred are epoxyfunctional vinyl monomers like glycidyl(meth)acrylate or3,4-epoxy-cyclohexylmethyl-acrylate. Preferably, the fatty acid isgrafted to the vinyl polymer by a condensation reaction or by a ringopening reaction.

In a preferred embodiment 30 to 70% of monomer G by weight of themonomers is used, before functionalisation to obtain an autoxidisablepolymer of the invention. Preferably the vinyl polymer comprisingmonomer G is then reacted with fatty acid, where typically between 0.4and 1.0 equivalent of fatty acid is reacted with the graftable groupspresent on the vinyl polymer. For this purpose, it is considered that ahydroxyl graftable group can react once with a fatty acid, whereas aepoxy graftable group can react twice, due to the additionally formedhydroxyl group on ring opening.

Preferably the autoxidisable polyvinyl polymer comprises <1% by weightof chlorine containing monomers.

Preferably the autoxidisable polyvinyl polymer comprises <40% by weightof styrenic monomers.

The autoxidisable polyvinyl polymer is preferably prepared by freeradical polymerisation, although in some circumstances anionicpolymerisation may be used. The free radical polymerisation can beperformed by techniques known in the art, for example as emulsionpolymerisation, solution polymerisation, suspension polymerisation orbulk polymerisation.

A free-radical polymerisation of vinyl monomer(s) to form anautoxidisable polyvinyl polymer or precursor autoxidisable polyvinylpolymer will require the use of a free-radical-yielding initiator(s) toinitiate the vinyl polymerisation. Suitable free-radical-yieldinginitiators include inorganic peroxides such as K, Na or ammoniumpersulphate, hydrogen peroxide, alkyl hydroperoxides such as t-butylhydroperoxide and cumene hydroperoxide; dialkyl peroxides such asdi-t-butyl peroxide and the like; mixtures may also be used. The peroxycompounds are in some cases advantageously used in combination withsuitable reducing agents (redox systems) such as Na or K pyrosulphite orbisulphite, and iso-ascorbic acid.

It may be desirable to control the molecular weight by addition of achain transfer agent to the free radical polymerisation process.Conventional chain transfer agents may be utilised and includemercaptans, sulphides, disulphides and halocarbons. In particularhowever the technique known as catalytic chain transfer polymerisation(CCTP) may be used to provide low molecular weights. In this case a freeradical polymerisation is carried out using a free radical forminginitiator and a catalytic amount of a selected transition metal complexacting as a catalytic chain transfer agent (CCTA), and in particular aselected cobalt chelate complex. Such a technique has been described forexample in N. S. Enikolopyan et al, J. Polym. Chem. Ed., Vol 19, 879(1981), U.S. Pat. No. 4,526,945, U.S. Pat. No. 4,680,354, EP-A-0196783,EP-A-0199436, EP-A-0788518 and WO-A-87/03605.

The use of catalytic chain transfer agents provide 4 important benefits:

-   a) very low concentrations of catalytic chain transfer agent    (typically 1 to 1000 ppm by weight of vinyl monomer used) are    required to attain the preferred low molecular weight oligomer and    do not have the odour often associated with conventional chain    transfer agents;-   b) an autoxidisable vinyl polymer prepared by CCTP contains a    terminal unsaturated group on many, if not every vinyl oligomer    molecule. This terminal unsaturation can participate in autoxidation    reactions for example in fatty acid crosslinking systems. Thus the    autoxidisable vinyl polymer of the present invention could have    autoxidisable crosslinker groups comprising the unsaturated groups    from fatty acids as well as terminal unsaturated groups resulting    from CCTP.-   c) CCTP allows the preparation of an autoxidisable vinyl polymer    which has a narrower PDi than is achievable by the use of    conventional chain transfer agents for low Mw autoxidisable polymer.-   d) Especially when epoxy functional monomers are used, CCTP has the    benefit compared to e.g. chain transfer agents with mercaptan    groups, that the CCTA does not react with the epoxy groups.

The solids content of the aqueous coating composition of the inventionmay be at least preferably ≧35% and more preferably ≧38% and/or may beno more than preferably ≦72%, more preferably ≦65% and most preferably≦63% by weight of the composition.

The autoxidisable polyvinyl polymer may be dispersed in water usingtechniques well known in the art. The crosslinkable autoxidisablepolyvinyl polymer normally does not require the use of an externalsurfactant when being dispersed into water because it contains polymerbound dispersing groups. Surfactants may be utilised in order to assistin the dispersion of the autoxidisable polymer in water. Suitablesurfactants include but are not limited to conventional anionic,cationic and/or non-ionic surfactants such as Na, K and NH₄ salts ofdialkylsulphosuccinates, Na, K and NH₄ salts of sulphated oils, Na, Kand NH₄ salts of alkyl sulphonic acids, Na, K and NH₄ alkyl sulphates,alkali metal salts of sulphonic acids; fatty alcohols, ethoxylated fattyacids and/or fatty amides, and Na, K and NH₄ salts of fatty acids suchas Na stearate and Na oleate. Other anionic surfactants include alkyl or(alk)aryl groups linked to sulphonic acid groups, sulphuric acid halfester groups (linked in turn to polyglycol ether groups), phosphonicacid groups, phosphoric acid analogues and phosphates or carboxylic acidgroups. Cationic surfactants include alkyl or (alk)aryl groups linked toquaternary ammonium salt groups. Non-ionic surfactants includepolyglycol ether compounds and polyethylene oxide compounds. Thesurfactants may also be polymeric surfactants which are also describedas wetting agents.

The amount of total surfactants used in aqueous compositions of theinvention is preferably at least ≧0.1%, more preferably ≧1%, and/or ispreferably no more than ≦7%, more preferably ≦4% and most preferably ≦2%by weight of the autoxidisable polyvinyl polymer. Preferably a mixtureof anionic and non-ionic surfactants are used.

If the aqueous composition comprising anionic surfactant, the anionicsurfactant may comprise ethylene oxide (EO) groups in an amount which ispreferably no more than ≦90%, more preferably ≦70%; most preferably ≦55%and/or is preferably at least ≧10% and/or ≧20% EO groups by weight ofthe surfactant. Preferred anionic surfactants comprise sulphate,sulphonate, phosphate and/or phosponate groups, more preferablyphosphate and/or phosponate groups.

Optionally to reduce the effect of cissing the composition comprisessurfactant in an amount of no more than preferably ≦5%, more preferably≦3%, most preferably ≦1.5% by weight of polyvinyl polymer solids.

Dispersants (such as dispersing compounds and/or dispersing resin) whichpreferably are autoxidisable (such as W-3000 available from Perstorp oras described in EP1870442) could also be employed instead of or combinedwith more conventional surfactants. Optionally where used the dispersant(such as a dispersing resin) is present in amount of at least preferably≧0.1%, more preferably ≧3% and most preferably ≧5% and/or no more thanpreferably ≦30%, more preferably ≦20% and most preferably ≦12% by weightof solid resin.

The aqueous coating composition of the invention is particularly usefulas or for providing the principle component of coating formulations(i.e. composition intended for application to a substrate withoutfurther treatment or additions thereto) such as protective or decorativecoating compositions (for example paint, lacquer or varnish) wherein aninitially prepared composition optionally may be further diluted withwater and/or organic solvents, and/or combined with further ingredientsor may be in more concentrated form by optional evaporation of waterand/or organic components of the liquid medium of an initially preparedcomposition.

An organic solvent may optionally be added before, during and/or afterthe polymerisation process for making the autoxidisable polymer and theaqueous coating composition to control the viscosity. Examples ofsolvents include water-miscible solvents such as propylene glycol basedsolvents, especially propylene glycol mono methyl ether and dipropyleneglycol mono methyl ether and glycol ethers such as butyl diglycol.Optionally no organic solvents are added.

A co-solvent, as is well known in the coating art, is an organic solventemployed in an aqueous composition to ameliorate the dryingcharacteristics thereof, and in particular to lower its minimum filmforming temperature. The co-solvent may be solvent incorporated or usedduring preparation of the autoxidisable polymer or may have been addedduring formulation of aqueous solution coating composition.

Preferably the aqueous coating composition has a co-solvent content≦15%, more preferably ≦10%, most preferably ≦6%, and especially ≦5% byweight of solids.

Preferably the aqueous coating composition has a co-solvent content ≧0%,more preferably ≧2% and most preferably ≧3.5% by weight of solids.

An advantage of the current invention is that co-solvent can, as isoften required for environmental and safety reasons, be present at avery low concentrations because of the plasticising nature of theautoxidisable polymer.

In general, aromatic or heterocyclic nitrogen-containing ligands (exceptpyridine) or aromatic and aliphatic primary and secondary (di)amineswere found to prolong the drying time to a considerable extent (asreported in Coordination Chemistry Reviews 249 (2005) 1709-1728). Anexample includes heterocyclic nitrogen-containing solvents such asN-methylpyrrolidone (NMP) and N-ethylpyrrolidone.

Preferably the aqueous coating composition comprises NMP in an amount ofno more than ≦13%, more preferably ≦10%, most preferably ≦5% andespecially ≦0.5% by weight of polymer solids.

Preferably the aqueous coating composition comprises only a small amountof nitrogen containing molecules with an evaporation rate ≦0.1, morepreferably ≦0.05 (as calculated below), the molecules being aromatic,heterocyclic or aliphatic primary and secondary di-amines where theweight % of nitrogen is ≧5% and more preferably ≧10%.

Preferably such nitrogen containing molecules are present in the aqueouscoating composition in an amount ≦13%, more preferably ≦8%, mostpreferably ≦5% and especially ≦0.5% by weight of polymer solids.

Values for evaporation rates were published by Texaco Chemical Companyin a bulletin Solvent Data; Solvent Properties (1990). These values arerelative to the evaporation rate of n-butylacetate for which theevaporation rate is defined as 1.00. Determination of evaporation ratesof solvents not listed in this bulletin is as described in ASTM D3539.

In an embodiment of the present invention there is provided an aqueouscoating composition comprising:

-   i) 35 to 50% of an autoxidisable polyvinyl polymer by weight of the    composition;-   ii) 0 to 20%, more preferably 0 to 15%, most preferably 0 to 10%,    especially 1 to 5% of co-solvent by weight of the composition; and-   iii) 35 to 65% of water by weight of the composition;    where i)+ii)+iii)=100%.

It is preferred to have <16 wt % on oligomer solids of a co-solvent withan evaporation rate between 0.05 and 0.005.

Preferably when the aqueous composition is formulated as paint, thecomposition comprises 2% to 10%, more preferably 3% to 9% of solvent byweight of the total paint composition. Preferably at least 50%, morepreferably ≧80%, most preferably ≧95% by weight of the total solvent aresolvent(s) having an evaporation rate (as defined herein) higher than0.012, more preferably from 0.018 to 0.25, most preferably lower than0.21.

The aqueous coating composition of the invention may be applied to avariety of substrates including wood, board, metals, stone, concrete,glass, cloth, leather, paper, plastics, foam and the like, by anyconventional method including brushing, dipping, flow coating, spraying,and the like. They are, however, particularly useful for providingcoatings on wood and board substrates. The aqueous carrier medium isremoved by natural drying or accelerated drying (by applying heat) toform a coating. Accordingly in a further embodiment of the inventionthere is provided a coating obtainable from an aqueous coatingcomposition of the present invention.

The aqueous coating composition of the invention may contain otherconventional ingredients including pigments, dyes, emulsifiers,surfactants, plasticisers, thickeners, heat stabilisers, levellingagents, anti-cratering agents, fillers, sedimentation inhibitors, UVabsorbers, antioxidants, dispersants, reactive diluents, waxes,neutralising agents, adhesion promoters, defoamers, co-solvents, wettingagents and the like introduced at any stage of the production process orsubsequently. It is possible to include fire retardants like antimonyoxide in the dispersions to enhance the fire retardant properties.

Preferred reactive diluents (which may or may not be the autoxidisable)may also have one or more of the following properties: M_(n)>1000 g/mol,more preferably >1500 g/mol and most preferably >2000 g/mol; M_(n)<5000g/mol, more preferably <4000 g/mol and especially <3500 g/mol; and/oroptionally (e.g. where the reactive diluent is autoxidisable) from 60 to90 wt %, more preferably 75 to 90%, most preferably 80 to 90% of fattyacid residues with an iodine value from 50 to 175, more preferably from80 to 150 g I₂/100 g by weight of sample.

If desired the aqueous dispersion of the invention can be used incombination with other polymer dispersions or solutions which are notaccording to the invention.

Compositions of the invention may comprise additional polymerdispersions or solutions not according to the invention preferably in anamount <35%, more preferably <20%, most preferably <10% and especially<4% by weight of total polymer solids. Mixtures of polymers according tothe invention can be used as well, where examples include mixtures basedon autoxidisable vinyl, polyester and/or polyamide polymers.

In particular, the aqueous coating compositions of the invention andformulations containing them advantageously include a drier salt(s).Drier salts are well known to the art for further improving curing inunsaturated film-forming substances. Generally speaking, drier salts aremetallic soaps, that is salts of metals and long chain carboxylic acids.It is thought that the metallic ions effect the curing action in thefilm coating and the fatty acid components confer compatibility in thecoating medium. Examples of drier metals are cobalt, manganese,zirconium, lead, neodymium, lanthanum and calcium. The level of driersalt(s) in the composition is typically that to provide an amount ofmetal(s) within the range of from 0.01 to 0.5% by weight based on theweight of autoxidisable polymer.

Drier salts are conventionally supplied as solutions in solvents for usein solvent-borne alkyd systems. They may, however, be used quitesatisfactorily in aqueous coating compositions since they can normallybe dispersed in such systems fairly easily. The drier salt(s) may beincorporated into the aqueous coating composition at any convenientstage. For example the drier salt(s) may be added prior to dispersioninto water. Drier accelerators may be added to the drier salts. Suitabledrier accelerators include 2,2′-bipyridyl and 1,10-phenanthroline.

Preferably the aqueous coating composition is a one component system,meaning that preferably no additional crosslinking agents, like forinstance polyaziridines, polycarbodiimides or polyisocyanates ormelamines are added to the aqueous coating composition, prior to theapplication of the coating to a substrate.

Preferably the aqueous coating composition is free from photoinitiatorsand is cured without the use of radiation curing equipment.

Another embodiment of the invention provides an aqueous (preferablysolution) coating composition as described herein (i.e. capable offorming coating films having a telegraphing value as defined herein ofless than 10 gloss units) where the autoxidisable polyvinyl polymer has:

-   i) fatty acid residue in an amount greater than or equal to 25% by    weight of said autoxidisable polyvinyl polymer;-   ii) a glass transition temperature (T_(g)) from −40° C. to +10° C.;-   iii) an acid value from 5 to 50 mg KOH/g;-   iv) a weight average molecular weight (M_(w)) from 6000 to 40000    g/mol; and-   v) a polydispersity (PDi) less than or equal to 20; and    where the composition has a co-solvent content <6% by weight of    solids.

In a further embodiment of the present invention there is provided anaqueous coating composition comprising:

-   i) 15% to 40%, more preferably 20% to 35 wt % of TiO₂;-   ii) 15% to 40%, more preferably 20% to 35% of polymer solids;-   iii) 0% to 10%, more preferably 0% to 7%, most preferably 0% to 5%    and especially 1% to 2.5% of co-solvent by weight of solids;-   iv) 0.1% to 3% of thickener;-   v) 0% to 5% dispersing agent;-   vi) 25% to 70% water;    where all percentages are by weight of the composition and    i)+ii)+iii)+iv)+v)+vi)=100%.

Preferably when the aqueous coating composition is formulated as apaint, the composition comprises 2 to 10% of co-solvent by weight ofpaint solids, preferably 3 to 9% of co-solvent, of which at least 50%,preferably at least 80% and most preferably at least 95% by weight hasan evaporation rate higher then 0.012, more preferably higher then 0.018and an evaporation rate lower then 0.25 and more preferably lower then0.21 (when compared to butyl acetate=1.0).

If vinyl monomers are used, preferably less then 10% and more preferredless then 5% of the autoxidisable polymer solids by weight shouldconsist of vinyl polymer material which is covalently bound to a fattyacid, where the covalent bond is generated through a grafting reactionof a propagating vinyl radical onto the unsaturated fatty acid. In thelatter case the fatty acid can either be a free unsaturated fatty acidor an unsaturated fatty which is part of a polymeric structure. Mostpreferably there is no grafting of vinyl monomers to the fatty acid atall.

Preferably the aqueous coating composition when coated onto a substrateis water resistant for 30 minutes, more preferably for 1 hour and mostpreferably for 3 hours after 24 hrs of drying the coating.

Preferably the aqueous coating composition when coated onto a substrateis block resistant at ambient temperature with a rating of 3 or more andmore preferably the coating is block resistant at 52° C. with a ratingof 3 or more after 24 hrs drying.

One aspect of the invention provides a method for preparing anautoxidisable polyvinyl polymer the process comprising the steps of:

-   I) polymerising ethylenically unsaturated vinyl monomers to form a    polyvinyl polymer; and-   II) reacting the polyvinyl polymer obtained in step I) with fatty    acids having an average iodine value in the range of 80 to 180 g    I₂/100 g fatty acid;    to obtain an autoxidisable polyvinyl polymer with the properties    described herein (such as being capable of forming a coating    composition which when in the form of the film has a telegraphing    value (as defined in claim 1) of less than 10 gloss units).

A further aspect of the invention provides a coating obtained and/orobtainable by a coating composition of the invention and having atelegraphing value (as defined herein) of less than 10 gloss units.

Another aspect of the invention provides a substrate coated with acoating of the invention.

A still other aspect of the invention provides a method of coating asubstrate comprising the steps of i) applying a coating composition ofthe invention to the substrate; ii) drying the substrate to form acoating thereon; where the coating has a telegraphing value (as definedherein) of less than 10 gloss units.

Yet another aspect of the invention provides use of an autoxidisablevinyl polymer and/or a coating composition of the invention for thepurpose of obtaining coatings having a telegraphing value (as definedherein) of less than 10 gloss units.

A still yet other aspect of the invention provides a method ofmanufacture of an autoxidisable vinyl polymer and/or a coatingcomposition of the invention for the purpose of obtaining coatingshaving a telegraphing value (as defined herein) of less than 10 glossunits.

Many other variations embodiments of the invention will be apparent tothose skilled in the art and such variations are contemplated within thebroad scope of the present invention. Further aspects of the inventionand preferred features thereof are given in the claims herein.

The present invention is now illustrated by reference to the followingnon-limiting example. Various registered trademarks, other designationsand/or abbreviations are used herein to denote some of ingredients usedto prepare polymers and compositions of the invention. These areidentified below by chemical name and/or trade-name and optionally theirmanufacturer or supplier from whom they are available commercially.However where a chemical name and/or supplier of a material describedherein is not given it may easily be found for example in referenceliterature well known to those skilled in the art: such as:‘McCutcheon's Emulsifiers and Detergents’, Rock Road, Glen Rock, N.J.07452-1700, USA, 1997 and/or Hawley's Condensed Chemical Dictionary(14th Edition) by Lewis, Richard J., Sr.; John Wiley & Sons.

-   ‘AIBN’ denotes azobisisobutyronitrile;-   ‘3,5-BHT’ denotes 3,5-di-tert-butyl-4-methylphenol (also known as    butyl hydroxy toluene);-   ‘BMA’ denotes n-butylmethacrylate;-   ‘CoF’ denotes the catalyst Co II (bis 4,4′-dimethylbenzil dioxime)    diborondifluoride, as described in EP1742973-A, US2007219328 and    WO2005105855;-   ‘Dowanol PnP’ denotes that p ‘Dowanol PnP’ denotes that propylene    glycol n-propyl ether mixture commercially available from Dow    Chemicals under this trade name;-   ‘FES 993’ denotes ammonium lauryl ether sulphate which is available    commercially from Cognis under the trade name Disponil FES 993 IS;-   ‘GMA’ denotes glycidyl methacrylate;-   ‘HHPA’ denotes hexahydro phtalic anhydride;-   ‘MMA’ denotes methyl methacrylate;-   ‘PAA’ denotes a polyacrylic acid with weight average molecular    weight (Mw) of from 200-250 KDalton which has been prepared by the    applicant;-   ‘PVC’ denotes polyvinyl chloride-   ‘TEA’ denotes triethyl amine;-   ‘THF’ denotes tetrahydrofuran; and-   ‘TRAP’ denotes triphenyl ethyl phosphonium bromide.    Test Methods:    Standard Conditions

As used herein, unless the context indicates otherwise, standardconditions (e.g. for drying a film) means a relative humidity of 50%±5%,ambient temperature (23° C.±2°) and an air flow of ≦0.1 m/s.

Particle Size

The particle sizes given herein are the size of a weight averagedparticle and are quoted as a linear dimension which is a particlediameter as the particles can be considered to be essentially spherical.Weight average particle size may be measured using Scanning/TransmissionElectron Microscope and Photon Correlation Spectroscopy.

Iodine Number

The iodine value (also referred to herein as iodine number) is a measureof the amount of ethylenic unsaturated double bonds in a sample andincreases with a greater degree of unsaturation. Iodine value may bedefined according to DIN 53241-1 as the quotient of that mass m_(I) ofiodine which is added on to the olefinic double bonds, withdecolorisation, of a sample to be analysed and the mass m_(B) of thissample (mass of the solid in the sample in the case of solutions ordispersions). Iodine values may be quoted either in units of centigramsof iodine per gram of sample (cg I₂/g) or in units of grams of iodineper 100 gram of sample (g I₂/100 g). Standard methods for analysis maybe used such as for example ASTM D5768-02(2006) and DIN 53241. Onecommon method (and that used to measure the iodine values given herein)is the Wjjs method in which iodine absorption is determined by titratingunreacted reagent with sodium thiosulfate and the iodine value is thencalculated as follows:

${{Iodine}\mspace{14mu}{value}} = \frac{(12.69) \times \left( {{ml}\mspace{14mu}{of}\mspace{14mu}{thiosulfate}} \right) \times ({normality})}{{mass}\mspace{14mu}{of}\mspace{14mu}{sample}\mspace{14mu}(g)}$Telegraphing

Two types of PVC substrates are used to determine the degree oftelegraphing of an unpigmented coating comprising the autoxidisableresin:

The first PVC type is the 2 mm thick rough PVC substrate with a welldefined and uniform rough surface that is available commercially fromVink Kunststoffen B.V (Didam, Holland) under the trade name Vikuporwhite PVC film type JD11. An area of 1.9×2.5 mm of the substrate surfaceis analysed with a Wyko optical profilometer NT1100 at a magnificationof 2.5 to give R_(z)=25 μm±5 μm. R_(z) denotes the ‘ten-point height’,which is the average of the five greatest peak-to-valley separations inthe scanned area, and is regarded as a general value for surfaceroughness. The second PVC type is a 3 mm thick smooth PVC substrate witha well defined smooth surface that is also available commercially fromVink Kunststoffen under the trade name Vikunyl white PVC film glossytype 206221. R_(z)=1 μm±0.25 μm (measured as for rough PVC).

The unpigmented coating comprising (optionally comprising flow andwetting agents and thickeners if needed) is cast on both PVC substrates(rough and smooth) and a smooth and defect free film is obtained,resulting in a theoretical dry film thickness between 52 μm±6 μm. Thefilm is dried under standard conditions for 24 hours and the gloss ismeasured at a 20° angle. This gloss measurement is repeated after 4days, 7 days and 14 days. The difference in gloss readings between thefilms on rough and smooth PVC is a quantitative measure of the extent towhich the rough surface of the PVC is telegraphed to the surface of thedried coating. The smaller the difference in these gloss values, thesmaller the degree of telegraphing and the better the coating hides thesubstrate roughness.

Also the absolute value for gloss reading on rough PVC should notdecrease significantly in time so that the reduced telegraphing ismaintained.

Drying Time:

To test the dust-free and tack-free drying stages of the aqueouscompositions prepared in the Example as described below, the aqueouscomposition is formulated and applied to a glass plate at a wet filmthickness of 80 μm. Tests for drying times are performed at regular timeintervals under standard conditions,

Dust-Free Time: The dust-free time is determined by dropping a piece ofcotton wool (about 1 cm³ i.e. 0.1 g) on to the drying film from adistance of 25 cm. If the piece of cotton wool can be immediately blownfrom the substrate by a person without leaving any wool or marks in oron the film, the film is considered to be dust-free.Tack-Free Time:

The tack-free time is determined by placing a piece of cotton wool(about 1 cm³, 0.1 g) on the drying film and placing a weight of 1 kgonto the piece of cotton wool (for 10 seconds). If the piece of cottonwool can be removed from the substrate by hand without leaving any woolor marks in or on the film, the film is considered to be tack-free.

Molecular Weight Determination:

Gel permeation chromatography (GPC) analyses for the determination ofpolymer molecular weights are performed on an Alliance Waters 2695 GPCwith three consecutive PL-gel columns (type Mixed-B, I/d=300/7.5 mm)using tetrahydrofuran (THF, HPLC grade, stabilized with3,5-di-tert-butyl-4-hydroxytoluene (BHT), preferably with 1.0 vol %acetic acid) as the eluent at 1 cm³/min and using an Alliance Waters2410 refractive index detector. A set of polystyrene standards (analysedaccording to DIN 55672) is used to calibrate the GPC. Samplescorresponding to about 16 mg of solid material were dissolved in 8 cm³of THF The samples were regularly shaken and dissolved for at least 24hours for complete “uncoiling” and placed on the auto-sampling unit ofthe Alliance Waters 2695. The injection volume was 150 μL and the columnoven was established at 35° C.

Glass Transition Temperature (T_(G))

The T_(g) was measured by DSC using the TA Instruments DSC Q1000 withthe standard TA Instruments alumina cups of 50 μl. The flow rate was 50ml/min of nitrogen and the sample was loaded at a temperature range 20to 25° C. The sample is cooled until it reached an equilibriumtemperature of −90° C. and then heated at a rate of 10° C./min to 100°C., kept for 5 minutes at 100° C., cooled to −90° C. at a rate of 20°C./min, kept for 5 minutes at −90° C. and subsequently heated at a rateof 10° C./min to 100° C.

Gloss Measurement Method:

Gloss measurements are carried out on a BYK Garnder micro-TRI-gloss20-60-85 glossmeter in accordance with ASTM D523-89.

EXAMPLE 1 1a Preparation of an Epoxy Functional Vinyl Polymer

A 2 L round bottom reactor, equipped with stirrer, baffle and cooler,was loaded with water (867.8 g), Na₂SO₄ (1.59 g) and PAA (0.79 g) undernitrogen. The mixture was neutralized with NaOH until pH>8 and broughtto 60° C. A homogeneous mixture of MMA (190.17 g), BMA (127.19 g) andGMA (317.99 g), AIBN (4.77 g) and CoPhMeBF (0.064 g) was transferred tothe reactor and the reaction temperature was brought to 80° C. After 90minutes a mixture of FES993 (0.53 g) and water (79.5 g) was added to thereactor. After another 10 minutes, the temperature was raised to 85° C.and kept at that temperature for 60 minutes. Subsequently, the reactorwas cooled to ambient temperature and the beads were washed and dried.

The Mn was 1736 g/mol, Mw was 3589 g/mol and the PDi was 2.07. The Tgwas 24° C. (midpoint) as measured by DSC.

1b Preparation of the Aqueous Autoxidisable Vinyl Polymer

The vinyl polymer prepared as described in step 1a above (500.0 g) wasdissolved in toluene (332.59 g). Sunflower fatty acid (492.85 g) andTRAP (4.93 g) were added to the resulting solution. The mixture washeated at 120° C. under nitrogen. The reaction was continued until theacid value reached 5.7 mg KOH/g.

The M_(n) was 2736 g/mol, M_(w) was 7662 g/mol and the PDi was 2.8. TheT_(g) was −12° C. (midpoint) as measured by DSC.

1c Functionalisation and Dispersing

HHPA (44.19 g) was added to the polymer solution resulting from step 1babove (340.0 g, 75% solids in toluene). The mixture was kept at 110° C.until virtually all anhydride was reacted as judged from the Infra Redspectrum of the reaction mixture (the anhydride groups typically showtwo absorptions at 1785 cm⁻¹ and 1865 cm⁻¹, which disappeared and werereplaced by a new ester carbonyl absorption at 1740 cm⁻¹). Then thetoluene was removed by distillation under reduced pressure to obtain afatty acid functional acrylic with an acid value of 59.4 mg KOH/g.Dowanol PnP (75.0 g) and TEA (28.9 g) was added to the fatty acidfunctional acrylic (300.0 g) followed by water (453.0 g) to obtain anaqueous composition having a 35% solid content, pH of 7.8 and T_(g)=−1°C. (midpoint) as measured by DSC.

TABLE 1 Properties example 1: Ex 1 Binder 100 Particle size [nm] <50Additol VXW4940/water 1:1 1.4 DFT [hr] 2 TFT [hr] 2.5 G(s) 83.2 G(r)79.0 Telg. 4.2 G decay (4 d) 6.7 G decay (7 d) 7.5 G decay (14 d) 8.9Key ‘DFT’ denotes dust free time defined and measured as describedherein ‘TFT’ denotes tack free time defined and measured as describedherein ‘G(r)’ denotes the initial rough gloss value as defined herein(measured in gloss units 1 day after film formation) ‘G(s)’ denotes theinitial smooth gloss value as defined herein (measured in gloss units 1day after film formation) ‘Telg.’ denotes the telegraphing value asdefined herein in gloss units (i.e. G(s)G(r)) ‘G decay (‘n’ d)’ denotesthe gloss decay value as defined herein after ‘n’ days (i.e. G(r) minusthe rough gloss measured ‘n’ days after film formation).

The invention claimed is:
 1. An aqueous coating composition thatcomprises an autoxidisable polymer that comprises plurality of vinylgroups where: I) said autoxidisable polyvinyl polymer has: i) fatty acidresidue in an amount greater than or equal to 20% by weight of saidautoxidisable polyvinyl polymer ii) a glass transition temperature (Tg)from 60° C. to +20° C.; iii) an acid value from 5 to 75; iv) a weightaverage molecular weight (Mw) from 2500 to 100000 g/mol; and v) apolydispersity (PDi) less than or equal to 30; II) said compositioncomprises: a) a co solvent content less than 25% by weight of solids; b)a solids content greater than or equal to 30% by the total weight ofsaid composition; c) 35% to 50% of the autoxidisable polyvinyl polymerby weight of the composition; d) 0 to 20% of co-solvent by weight of thecomposition; and e) 35% to 65% of water by weight of the composition;and III) said composition when in the form of a film has a telegraphingvalue of less than 10 gloss units, wherein the telegraphing value is adifference between an initial smooth gloss value of the film minus aninitial rough gloss value of the film, where (1) the initial smoothgloss value is the gloss when the film is cast on a smooth PVC substratewith Rz=1 μm±0.25 μm and the initial rough gloss value is the gloss whenthe film is cast on a rough PVC substrate with Rz=25 μm±5 μm, wherein Rzis an average of five greatest peak-to-valley separations in a scannedsurface area of 1.9×2.5 mm of the PVC substrate as analyzed with anoptical profilometer at a magnification of 2.5; (2) each film has a dryfilm thickness of 52 μm±6 μm; and (3) each initial gloss value ismeasured at a 20° angle, 24 hours after the film has been cast onto thePVC substrate.
 2. The aqueous coating composition according to claim 1,wherein the autoxidisable polymer if carboxylic acid functional has anND x AV value of >22 and <65; where ND=neutralization degree of the acidgroups on the polymer and AV=acid value.
 3. The aqueous coatingcomposition according to claim 1, wherein the composition comprises <13%N methylpyrrolidone by weight of the composition.
 4. The aqueous coatingcomposition according to claim 1, wherein the coating compositioncomprises <13% by weight of polymer solids of nitrogen containingmolecules with an evaporation rate <0.1 as determined by ASTM D3539relative to the evaporation rate of n-butyl acetate=1.00 which areeither aromatic, heterocyclic or which are aromatic and aliphaticprimary and secondary (di)amines with the proviso that the weight % ofnitrogen in such molecules is >5%.
 5. The aqueous coating composition asclaimed in claim 1, wherein the autoxidisable polyvinyl polymer has: i)fatty acid residue in an amount greater than or equal to 25% by weightof said autoxidisable polyvinyl polymer; ii) a glass transitiontemperature (Tg) from 40° C. to +10° C.; iii) an acid value from 5 to 50mg KOH/g; iv) a weight average molecular weight (Mw) from 6000 to 40000g/mol; and v) a polydispersity (PDi) less than or equal to 20; andwherein the composition has a co solvent content <6% by weight ofsolids.
 6. The aqueous coating composition according to claim 1,comprising: i) 15% to 40% of TiO2; ii) 15% to 40% of polymer solids;iii) 0 to 10% of co solvent by weight of solids; iv) 0.1 to 3% ofthickener; v) 0 to 5% dispersing agent; vi) 25% to 70% water; whereinunless indicated all percentages are by weight of the composition andi)+ii)+iii)+iv)+v)+vi)=100%.
 7. The aqueous coating composition asclaimed in claim 1, wherein the acid value of the autoxidisablepolyvinyl polymer is from 15 to 75 mg KOH/g.
 8. A method of coating asubstrate comprising the steps of: i) applying a coating composition asclaimed in claim 1 to a substrate; and ii) drying the substrate to forma coating thereon; wherein the coating has a telegraphing value of lessthan 10 gloss units.